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Conjunctivitis is an inflammation of the conjunctiva. The conjunctiva is the thin layer of tissue covering the whites of your eye and lining the inner portion of your eyelids. Most people consider pink eye a contagious infection, but not all forms of conjunctivitis are infectious.
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These are the most frequent causes of conjunctivitis:
Viruses cause around 80 percent of acute conjunctivitis cases.
Viral, bacterial, and allergic conjunctivitis often cause similar symptoms, but some key features can help you distinguish one from the other.
Viral. You may notice burning, light sensitivity, redness, clear discharge, and swollen eyelids. You may have swollen and tender preauricular lymph nodes, which are located right in front of your ears. An indication you may have viral conjunctivitis is if you had a cold recently or were exposed to someone sick. Viral conjunctivitis often starts in one eye and spreads to the other eye.
Bacterial. Symptoms include redness, pain, burning, and swollen eyelids. Because some signs are similar to viral conjunctivitis, it can be difficult to tell the difference. However, bacterial conjunctivitis also causes sticky pus to develop in the eye. This discharge can be white, yellow, or green. Generally, bacterial conjunctivitis does not cause swollen preauricular lymph nodes. Although bacterial conjunctivitis typically occurs in one eye, the other eye can become infected.
Allergic. A primary distinction between allergic and viral or bacterial conjunctivitis is that allergies tend to cause itching. Other symptoms include redness, tearing, light sensitivity, and swollen eyelids. Some people also notice white, stringy discharge, but most have a clear, watery discharge. Allergic conjunctivitis usually occurs in both eyes. You may also have symptoms of sinus congestion, sneezing, or a runny nose.
Viral conjunctivitis is highly contagious. Adenovirus spreads through close personal contact, through the air via respiratory droplets, or touching contaminated surfaces. Bacterial conjunctivitis spreads via personal contact, touching contaminated surfaces, and respiratory droplets.
In some cases, changes to your eye’s normal bacterial flora can also cause pink eye. Allergic pink eye is not contagious.
If you think you may have conjunctivitis, especially a contagious type, consult your eye doctor. In the meantime, be careful not to spread the infection to others. Avoid going to work or school, and try not to contaminate any surfaces someone else may touch. Remove your contact lenses immediately and only use your eyeglasses.
Your eye doctor can examine your eyes to determine what kind of conjunctivitis you have. Your symptoms and health history give the doctor useful information to help make the diagnosis.
During the exam, they use an instrument called a slit-lamp to view your eyes under magnification. A yellow-colored eye drop called fluorescein helps the doctor look for signs of eye irritation or injury while examining your eyes in the slit-lamp. They may also check your preauricular lymph nodes for any swelling.
Practicing excellent hygiene is the best way to prevent infectious types of conjunctivitis, including viral and bacterial. Here are some prevention tips:
Additional tips to reduce your risk of allergic conjunctivitis:
Many cases of conjunctivitis are self-limiting, which means the condition resolves on its own without treatment. However, it is best to consult your eye doctor for a diagnosis and the appropriate treatment plan, if needed.
Treatment is usually not required. Viral conjunctivitis is contagious for about 12-14 days and may last up to three weeks. Unfortunately, there is no treatment to shorten the duration of the infection, only therapy focused on symptomatic relief. You can use cool compresses and lubricating drops if your eyes feel irritated. Depending on the severity of inflammation, your doctor may prescribe anti-inflammatory eye drops.
This condition is usually self-limiting and resolves in two weeks. However, most eye doctors prescribe antibiotic eye drops or ointments that reduce the duration to only a few days. Keeping the eye area clean and free of discharge is also ideal. If the infection is severe, especially in children, the eye doctor may prescribe oral antibiotics.
Non-medicated therapies include cool compresses and lubricating drops. Oral allergy medication may also provide relief. If your allergies persist, the eye doctor can prescribe anti-inflammatory or antihistamine eye drops. Avoiding the source of your allergies is the best way to alleviate allergic conjunctivitis.
Azari, Amir A., and Neal P. Barney. “Conjunctivitis.” JAMA, vol. 310, no. 16, 23 Oct. 2013, pp. 1721–1729., doi:10.1001/jama.2013.280318.
Kaiser, Peter K., and Neil J. Friedman. The Massachusetts Eye and Ear Infirmary Illustrated Manual of Ophthalmology. Saunders, Elsevier, 2009.
Varu, Divya M., et al. “Conjunctivitis Preferred Practice Pattern.” Ophthalmology, vol. 126, no. 1, 2018, pp. 95–169., doi:10.1016/j.ophtha.2018.10.020.